Add packed add and subtract to IA32 and X64 assemblers

runtime/vm/disassembler_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/disassembler.h"
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_X64)
 #include "platform/utils.h"
 #include "vm/allocation.h"
@@ skipping 1264 matching lines @@
         } else if (opcode == 0x54) {
           mnemonic = "andpd";
         } else  if (opcode == 0x56) {
           mnemonic = "orpd";
         } else  if (opcode == 0x57) {
           mnemonic = "xorpd";
         } else if (opcode == 0x2E) {
           mnemonic = "ucomisd";
         } else if (opcode == 0x2F) {
           mnemonic = "comisd";
+        } else if (opcode == 0xFE) {
+          mnemonic = "paddd";
+        } else if (opcode == 0xFA) {
+          mnemonic = "psubd";
         } else {
           UnimplementedInstruction();
         }
         AppendToBuffer("%s %s,", mnemonic, NameOfXMMRegister(regop));
         current += PrintRightXMMOperand(current);
       }
     }
   } else if (group_1_prefix_ == 0xF2) {
     // Beginning of instructions with prefix 0xF2.
 
@@ skipping 633 matching lines @@
                                   pc);
     pc += instruction_length;
   }
 
   return;
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64